There is a great demand for protection of potable water from contamination with impurities. Basic movement of water in the earth's soil, either vertically or horizontally, when interfaced with a source of contamination, requires that the contamination be contained and that any contaminated water be recovered and treated to an acceptable standard so that the recovered water can be reintroduced into the water cycle. Great efforts have been expended to design and construct various leachate and polluted water containments, coupled with recovery and treatment methods for these waters.
Various attempts have been made to effectuate this goal by a leachate containment system. Some examples are:
U.S. Pat. No. 4,252,462 to Klingle et al. discloses a landfill for permanent disposal of waste water sludge. An impoundment area is formed having a base that is substantially liquid impervious. A liquid collection system and conveyance is installed in liquid pervious materials which overlay the impervious base. The landfill is designed to be closed after sludge is dewatered by spreading a liquid impervious layer over the dewatered sludge.
U.S. Pat. No. 4,296,884 to Luebke discloses a containment reservoir and method. A reservoir is constructed of an impervious liner following the contours of earthen construction and having a covering layer of pervious fabric material for filtering liquids passing into the reservoir. This system includes drain recovery pipes which provide that liquid that is caught in the reservoir will drain by gravity down through a drain section, down a passageway where it is removed by gravity to a more remote location or storage facility. The system is a fully constructed system located only a few feet in depth from normal land surface elevation and is primarily addressed at retaining or salvaging spilled oil along a railroad track environment.
U.S. Pat. No. 4,352,601 to Valiga et al. discloses a permanent bin for temporary storage of hazardous materials. This is a fully constructed system which is to be installed at a level which is above the high water table level in the region.
The system incorporates an excavated basin, drainage trench, and a continuous preformed liner of water impervious plastic, or asphaltic liquids applied in sufficient depth to establish a suitable water impervious barrier. A drainage collection system, including perforated pipes, is installed in the drainage ditch. A cementitious covering forming an impervious layer is placed over the plastic or asphaltic liner in berm slopes. The drainage pipe is sealed from the containment by the liner and cementitious covering and is used for monitoring of leakage from the constructed storage bin. The drainage flows by gravity to a collector pump located outside the perimeter wall. This system is a fully constructed storage barrier to contain hazardous wastes placed therein and is designed to contain 100% of material, liquid or otherwise, and a monitoring method for leakage.
U.S. Pat. No. 4,358,221 to Wickberg discloses a system for pollution control. This system relates to dump sites for chemical and toxic wastes which avoid the usual problems of chemical pollution of ground water. The system is installed in areas where there exists impermeable layers of clay or other materials which preclude the need for bottom lining.
The system includes a precast section of tongue and groove concrete barrier walls to complete the sealed containment. The containment is extended to the aquaclude and driven into place. Vertical sand filled columns are interconnected by gravel filled rows forming a common drainage network to a collection pit. This system provides for a place to deposit waste slurries and leachate collecting therefrom by wicks interconnected and gravity conveyed to a collector pit for removal.
U.S. Pat. No. 4,366,846 to Curati, Jr., discloses a method for collecting and storing liquid from along a railroad track section. This system provides for a containment and storage system for liquids.
The system includes a walled containment reservoir formed underground by means of an impervious liner and a receiving and storage area. Parallel perforated collecting pipes are interconnected and gravity fed to common manhole reservoirs which become pump out points for the collected liquids. The collecting pipes are covered by a pervious layer of non-woven fabric material as a filter.
Some examples of a system for installation of a leachate containment system are:
U.S. Pat. No. 3,182,459 to Grether et al., provides for forming of a continuous opening in the soil along a path where one desires to erect a water barrier, positioning a continuous sheet of plastic film vertically above the soil opening with the lower edge of the film extending into the opening, partly or completely filling the soil opening to form a substantially fluid-tight seal between the plastic film and the soil, and positioning rigid uprights adjacent the soil opening and fastening the vertically disposed film to the uprights.
This system is primarily addressed to extend the barrier above the ground surface for impounding water on the surface and having reinforcement staking for this purpose. The barrier seal into the ground surface is less than the portion supported by the stakes above ground. Further, the trench for the buried barrier is about 11/2 inches wide and about 9 inches deep. This system is specifically for a synthetic levee for rice fields. All of the plastic film handling is primarily at ground level and at very shallow depths.
U.S. Pat. No. 4,337,006 to Lacey discloses a device for preparing and cleaning a trench for an aquifer recharging system. This system provides a means of lining a trench on one or both walls with a membrane impervious to water so that water can be confined either in a specific place or outside a certain space. The device may be used in conjunction with a trencher and requires no separate power means although it may also be used separately. The lining mechanism is rolls of impermeable liner material encased in a trench box, with seals to prevent soil intrusion. The liner material is fed out into position to line the trench wall or walls, as may be desired.
The trench is filled with pea gravel above the natural soil's gravel pack and topped with a fine filter sand bed. The cleaning of the aquifer recharge bed is addressed to surface sediments collected on the top filter sand bed. It is a hooded device of sufficient width to cover the width of the filter bed trench, an agitator, and vacuum pump which lifts the impurities (sediments). Water is entrained and passes through a separating device which floats off and captures the filtered sand for replacement on the trench.
This system requires an open free-standing ditch to accommodate the liner placement box, subsequently backfilled with imported selected materials and does not require a bottom sealing method to the parent soils encountered. The cleaning mechanism requires the filter trench to be submerged and special surface constructed and maintained concrete curbings on which the cleaning and liner mechanism may travel.
U.S Pat. No. 4,484,835 to van Klinken discloses a method and apparatus for installing a ground water barrier. This system provides for the insertion of vertical sheets of material of an impervious nature by a lance which is vibrated into the ground to the desired depth. The width of the sheet and the lance, respectively, is at least one meter and preferably many meters. The sealing method of the vertical joints is possible by the overlapping and soil pressure seals, inflatable end strips, or by filling end strips with a solution which expands and hardens into place. The system utilizes a movable crane with a crane jib and a vibrating mechanism attached thereto.
U.S. Pat. No. 4,607,981 to van Klinken discloses a method for constructing a screen that obstructs the flow of subsoil water. This system is an improvement on van Klinken's earlier patent and is addressed towards a better method of vertical joint sealing. This system provides for an interlocking of the vertical panel edges in the manner of standard sheet piling, to resist separation thereof.
U.S Pat. No. 4,720,212 to Steenbergen et al. discloses a method and appliance for laying a sheet of material in the ground. By this system, a sheet of material is laid in the ground by digging a trench in the ground by a trench digger and unwinding the sheet of material from a stock roll above ground level, passing the sheet of material into the trench in a downward direction and diverting it in a direction essentially parallel to the ground level.
The sheet material is impervious or pervious filter cloth material which is laid flat at the bottom of an inverted "T" trench. The inverted "T" trench is formed by a digging beam provided at its lower end with laterally projecting digging screws. A protective housing includes a cross section in the form of an inverted "T".
The sheet material is carried by the trencher in rolls and is folded as it is fed into the trench box and unfolded and laid flat and horizontally at the bottom of the inverted "T" trench. No provision is made for joining a vertical wall installation to the horizontally flat sheet material.
U.S. Pat. No. 4,543,016 to Tallard discloses an underground leachate barrier and method of making same. This system provides for an impermeable barrier to be installed in a trench, securing the barrier by an impervious plug on the trench bottom and installing a drainpipe and filter gravel as trench/collection components.
This process includes an excavation of an open trench area, an installation of a liner on a good water side in the trench excavation and filling the trench with biodegradable slurry, pouring pelletized bentonite, expansive clay, or resin emulsion into the trench bottom in a slurry form to form a bottom plug seal, installation of a collector header and periodic risers, and backfilling pervious filter gravel into the trench where it is mixed with the biodegradable slurry. The trench depth is to impermeable soils or aqualude.
The foregoing patents are addressed to limited applications seeking to provide total containment with extensive, costly construction processes, most of which are surface area oriented.